Means for grounding a shielded cable

ABSTRACT

A pair of concentric hollow metallic sleeves are provided with sheath engaging means which may be in the form of raised protrusions disposed on one or both of the opposing surfaces of said sleeves to engage and electrically join the sheath of a sheathed cable to an external conductor upon the radial compression of the outer one of said sleeves after positioning a portion of the sheath and the external conductor within the annular gap existing between said sleeves. The resulting composite structure provides secure mechanical and electrical engagement between the external conductor, the sheath of the sheathed cable and the inner and outer metallic sleeves while additionally providing a smooth burr-free termination thereat. The sheath engaging means may comprise a series of raised ridges extending either parallel to the longitudinal axis of each of the sleeves or oblique thereto in selective patterns. The inner or outer sleeves may be further provided with selectively formed recesses designed to at least partially encompass the external conductor while additional recesses may be provided within the outer surface of the outer sleeve to relieve the stress formed thereby by the compression of the outer sleeve about the inner sleeve.

[451 July 29,1975

Haitmanek MEANS FOR GROUNDING A SHIELDED CABLE [75] Inventor: Louis F.Haitmanek, Florham Park,

[73] Assignee: Thomas & Betts Corporation,

Elizabeth, NJ.

[22] Filed: Mar. 8, 1974 [21] Appl. No.: 449,270

[52] US. Cl. 339/97 C; 339/223 R; 339/276 R [51] Int. Cl. ..H01R 11/08;HOlR 1l/20 [58] Field of Search 339/97 R, 97 C, 98, 220 R, 339/223 R,276 R, 276 T [56] References Cited UNITED STATES PATENTS 2,890,2676/1959 Forney 339/276 R X 2,901,528 8/1959 Lazar.... 33 /223 R X3,546,365 12/1970 Collier 339/276 R X 3,549,787 12/1970 Churla 339/223 RX Primary ExaminerRoy Lake Assistant Examiner-E. F. Desmond Attorney,Agent, or Firm-David Teschner; Jesse Woldman [57] ABSTRACT A pair ofconcentric hollow metallic sleeves are provided with sheath engagingmeans which may be in the form of raised protrusions disposed on one orboth of the opposing surfaces of said sleeves to engage and electricallyjoin the sheath of a sheathed cable to an external conductor upon theradial compression of the outer one of said sleeves after positioning aportion of the sheath and the external conductor within the annular gapexisting between said sleeves. The resulting composite structureprovides secure mechanical and electrical engagement between theexternal conductor, the sheath of the sheathed cable and the inner andouter metallic sleeves while additionally providing a smooth burr-freetermination thereat. The sheath engaging means may comprise a series ofraised ridges extending either parallel to the longitudinal axis of eachof the sleeves or oblique thereto in selective patterns. The inner orouter sleeves may be further provided with selectively formed recessesdesigned to at least partially encompass the external conductor whileadditional recesses may be provided within the outer surface of theouter sleeve to relieve the stress formed thereby by the compression ofthe outer sleeve about the inner sleeve.

3 Claims, 14 Drawing Figures PATENTEDJULZSISYS 3, 897, 127

SHEET 1 if E1- K//////////7 MEANS FOR GROUNDING A SHIELDED CABLEBACKGROUND OF THE INVENTION 1. Field of the Invention The invention isdirected to the field of connectors and principally to means forgrounding the sheath of a sheathed cable.

2. Description of the Prior Art With the increasing use of aluminum inthe manufacture of electrical cables and specifically as a sheathmaterial for shielded cable many problems have arisen in the field ofterminating devices adapted to join the cable sheath to an externalconductor for the purpose, for example, of connecting the sheath to acommon ground point. Although a variety of terminating devices have beendesigned to accomplish this purpose, and include assemblies requiringthe sheath to be separated from the remainder of the cable and formedinto a taillike extension for insertion within the barrel of a terminalor the like, the employment of such devices has often proved to be quitecumbersome, inefficient, and of a relatively primitive nature.Furthermore, these devices generally require that the smooth contour ofthe cable be disturbed to effect the aforementioned connection, anarrangement which may cause serious difficulties in high frequencyapplications. More recent devices have attempted to overcome thislimitation by providing, for example, a pair of concentric rings adaptedto provide a sandwich-like assembly comprising the cable sheath and theexternal conductor interposed between the concentric rings or sleeveswhereby an electrical connection is formed by compressing the outersleeve radially inwardly towards the inner sleeve. Although sucharrangement has found a measure of success in use, the increasingemployment of aluminum sheath material has resulted in a high failurerate with respect to such grounding means since the relatively smoothopposing surfaces of the inner and outer sleeve members may provide amechanically secure assembly, such surfaces are ineffective inpenetrating insulative coverings such as the oxide coating of analuminum sheath to establish electrical contact with the underlyingconductive portion thereof.

SUMMARY OF THE INVENTION The invention overcomes the limitations anddifficulties noted above with respect to prior art devices by providingimproved means for joining an external conductor to the sheath of ametallically sheathed cable to insure a positive electrical andmechanical connection therebetween in a manner more reliable, efficient,and convenient than such prior art devices. A pair of hollow, metallic,concentrically disposable sleeve members are selectively dimensioned toprovide an annular gap therebetween adapted to receive both the sheathof a metallically sheathed cable and an external conductor therebetween.Either one or both of the opposing surfaces of the sleeve members may beprovided with a sheath engaging means which may take the form preferablyof a series of selectively formed raised ridges adapted to engage theinterposed sheath and external conductor upon compression of the outermetallic sleeve radially inwardly against the inner sleeve. One or moreselectively dimensioned recessed portions may be provided between theridges to provide a discreet pocket for the external conductor. Theouter periphery of the second or outer metallic sleeve may be suitablyslotted or grooved to provide reduced cross sectional areas forrelieving the stress generated in the outer sleeve by the radialcompression thereof. The inner and outer metallic sleeves may be formedof similar electrically conducting material with the inner sleeve havinga substantially greater hardness to provide an anvil-like abuttmentagainst which the outer sleeve may be compressed to effect theelectrical assembly. Thus, for example, the inner sleeve may be formedfrom full hard brass material while the outer sl eve is formed from arelatively soft copper or copper alloy. It is therefore an object ofthis invention to provide an improved connector.

It is another object of this invention to provide means for insuringelectrical integrity between the aluminum sheath of a shielded cable andan external conductor.

It is yet another object of this invention to provide means forconnecting the sheath of a sheathed cable to an external conductor withminimum deformation of the sheath.

It is a further object of this invention to provide an improvedconnection between the sheath of an aluminum sheathed cable and anexternal conductor.

It is yet another object of this invention to provide a concentric ringassembly having sheath engaging means for electrically connecting thealuminum sheath of a sheathed cable to an external conductor.

Other objects and features will be pointed out in the followingdescription and claims and illustrated in the accompanying drawingswhich disclose, by way of example, the principle of the invention andthe best mode contemplated for carrying it out.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings FIG. 1 is a sideelevational view, partially cut away and partly in section, showing anexternal conductor connected to the sheath of a metallically sheathedcable by means constructed in accordance with the concepts of theinvention.

FIG. 2 is a fragmentary sectional view of a portion of the assemblyillustrated in FIG. 1.

FIG. 3 is a fragmentary sectional view of a portion of the second sleevemember of the device illustrated in FIG. 1, showing sheath engagingmeans located about the inner surface thereof.

FIG. 4 is a fragmentary sectional view of a further embodiment of thesecond sleeve member of means constructed in accordance with theconcepts of the invention.

FIGS. 5, 6 and 7 are fragmentary views showing further embodiments ofthe sheath engaging means as employed with a device constructed inaccordance with the concepts of the invention.

FIG. 8 is a fragmentary sectional view of a further embodiment of thefirst sleeve member of a device constructed in accordance with theconcepts of the invention.

FIG. 9 is an enlarged fragmentary sectional view showing a portion ofthe assembly illustrated in FIG. 1, preparatory to completion of theconnection.

FIG. 10 is an enlarged fragmentary sectional view showing the assemblyillustrated in FIG. 9 after completion of the connection.

FIG. 11 is an enlarged fragmentary sectional view showing the manner inwhich recessed portions in the second sleeve member may be employed toengage an external conductor prior to compression.

FIG. 12 is an enlarged fragmentary sectional view showing the assemblyof FIG. 11 after compression.

FIG. 13 is an enlarged fragmentary sectional view of a furtherembodiment of a second sleeve member constructed in accordance with theconcepts of the invention.

FIG. 14 is an enlarged fragmentary sectional view showing the secondsleeve member of FIG. 13 after compression.

Similar elements are given similar reference characters in each of therespective drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIGS. 1 and 2there is shown a connecting means 20 constructed in accordance with theconcepts of the invention, for joining an external conductor 22 to asheath 24 of a metallically sheathed cable 26. Means 20 comprises a pairof concentric elements including an inner or first sleeve member 28 anda second or outer sleeve member 30. Sleeves 28 and 30 may be of almostany convenient width although it is preferable that the first sleevemember 28 be at least as wide as the second sleeve member 30.Additionally, due to the nature of the assembly and the manner in whichit is employed to effect the desired connection, the first sleeve member28 is constructed of metallic stock having a hardness greater than thesecond sleeve member 30 so as to provide an anvil-like support as thesecond sleeve member 30 is compressed thereagainst. It has been found,for example, that a first sleeve member constructed of full hard brasswill provide a satisfactory support for a second sleeve memberconstructed preferably from soft copper or copper alloy. To increase theelectrical engagement between the sleeve members 28 and 30, theinterposed sheath 24, and the external conductor 22, either or both ofthe opposing surfaces of the sleeve members 28 and 30 are provided withsheath engaging means as illustrated, for example, in FIG. 3 wherein theinner surface of the second sleeve member 30 is shown provided with aseries of ridges 32 extending above the inner surface of the sleevemember 30 and adapted to penetrate the outer surface of the sheath 24 toa predetermined depth to provide increased electrical engagement withthe inner portion thereof. Thus, in the case where the sheath 24 isformed from aluminum material, the ridges 32 provide means forpenetrating the outer oxide coating of the aluminum to engage theconductive portion therewithin. The ridges 32 may extend generallyparallel to the longitudinal axis of the second sleeve member 30 and maybe disposed either uniformly about the inner surface thereof or in agiven pattern comprising spaced groups thereof in either a uniform ornon-uniform arrangement according to the application and within theconcepts herein disclosed. Accordingly, the inner circumferentialsurface of the second sleeve member 30 may include ridges 32 disposed ingroups of two or more of such ridges, each group occupying radialsegments of from to the full 360 of arc of the inner surface of thesleeve member. Moreover, the ridges 32 may extend continuously acrossthe inner surface of the second sleeve member or may comprise a seriesof interrupted portions (not shown) approximating individual teeth.Furthermore, the orientation and shape of the ridges 32 may be modifiedas shown, for example, in FIGS. 5, 6 and 7, at 34, 36 and 38,respectively, wherein ridges 34 are shown extending undulatingly acrossthe sleeve surface, ridges 36 are shown extending across the sleevesurface at an oblique angle to the longitudinal axis of the sleevemember, and ridges 38 are shown extending generally arcuately across thesleeve surface. It will of course be clear that the ridges 34, 36 and 38may also be arranged in selective groups comprising a single pattern orcombination of configurations, as necessary or desirable. As furtherillustrated in FIG. 4, the ridges may be formed as a series oftriangular teeth 40 similarly adaptable for employment as sheathengaging means. Those skilled in the art will further appreciate thatalthough only two basic ridge configurations have been illustrated anddescribed herein, other suitable configurations adapted to function assheath engaging or insulation piercing means maybe provided in similarmanner for the purposes herein disclosed. As further illustrated in FIG.3, there may be additionally provided recesses such as 42 interspersedbetween adjacent ridge pairs 32 for accommodating the bared portion ofthe external conductor 22, in the manner shown in both FIGS. 9 and 11.As further illustrated in FIGS. 9 and 11, respectively, the width of therecess 42 may be selected so as to either completely or partiallyaccommodate the conductors 22 before compression of the second sleevemember 30 thereabout. The additional advantages of the arrangement shownin FIG. 11 will become more apparent as the operation of the device isexplained in further detail hereafter. The second sleeve-member 30 maybe further modified as illustrated, for example, in FIG. 13 where thereis shown an additional series of recesses 44 extending generallytransversely across the outer surface 46 of a second sleeve member 48.The recesses 44 may be selectively located at desired positions aboutthe periphery of the second sleeve member 48 not only to assist inproviding a more uniform collapse of the second sleeve member upon itscompression against the first sleeve member 28, but also to relieve thestress induced in the second sleeve member 48 upon such compression byproviding reduced cross sectional areas thereat. Accordingly, uponcompression of the second sleeve member 48, the sidewalls defining therecesses 44 converge towards one another, as illustrated in FIG. 14, inresponse to the stress exerted on the second sleeve member 48 duringcompression.

Turning now specifically to FIG. 2, upon the inward radial compressionof the outer sleeve member 30, the encompassed sheath 24 and theexternal conductor 22 are caused to be sandwiched between the outersleeve member 30 and the inner sleeve member 28, substantially as shown.Portions of the sheath 24 are, accordingly, displaced and locked intothe areas between the ridges 32 to provide increased mechanical andelectrical engagement between the second sleeve member 30, the sheath24, and the first sleeve member 28. The external conductor 22, beinginterposed between the sheath 24 and the second sleeve member 30, is,accordingly, tightly confined between said elements to insure electricalengagement at least with the outer or second sleeve member 30. Thus,although the presence of an oxide film on an aluminum sheath may hinderdirect electrical contact between the external conductor 22 and thesurface of the sheath 24 these two elements are electrically joined toone another at least through the second sleeve member 30. Where theexternal conductor 22 is inserted in a recess 42 having a width largerthan the diameter of the conductor, as in the case illustrated in FIG.9, compression of the second sleeve member 30 causes the conductor 22 tobe deformed within the recess 42 substantially as shown in FIG. 10, andurged against the side walls thereof partly as a result of thedisplacement of the sheath 28 into the recess 42 and partly as a resultof the contraction of the recess 42 upon compression of the assembly.Where, however, the conductor diameter is greater than the width of therecess 42 into which it is inserted so as to be only partiallyencompassed thereby, as illustrated in FIG. 11, upon compressivedeformation of the second sleeve member 30 the ridges 32 flanking theassociated recess 42 are caused to bite into the sides of the externalconductor 22 in a manner more clearly seen in FIG. 12, thus insuringthat adequate electrical engagement between the second sleeve member 30and the conductor 22 is provided in those cases where the engagedportion of the conductor 22 has an oxide or other insulative filmthereabout. It should further be noted that the recesses 42, althoughhaving an essentially rectangular shape in their undeformed state, arecaused to deform in such manner as to provide an essentially truncatedtriangular pocket, in section, thus securely locking the sheath 24 tothe second sleeve member 30 and preventing movement or displacement ofthe sheath 24 with respect to the outer sleeve member 30 during handlingand use. This arrangement also insures that the entrapped portions ofthe sheath member 24, as shown at 50 in FlG. 12, will tend to expand andcontract within the pockets formed by the recesses 42 to insurepermanent electrical contact with the second sleeve member 30 duringthermal cycling of the assembly.

Referring now to FIG. 8 there is shown a further embodiment of a firstor inner sleeve member 52 constructed in accordance with the concepts ofthe invention. The first sleeve member 52 comprises an outer surface 54on which are disposed a series of ridges 56 essentially duplicative ofthe ridges 32 described hereinabove. Accordingly, the ridges 56 willoperate in a manner similar to that described above with respect to theridges 32 to effect engagement with the sheath 24 upon compression ofthe outer sleeve member thereagainst. Furthermore, the ridges 56 may beoriented and positioned as described heretofore with respect to theridges 32. It will thus be clear that either or both inner and outersleeve members may be provided with sheath engaging means to provide thenecessary electrical connection between the sheath 24 and the externalconductor 22. As will be apparent from the embodiment illustrated inFIG. 8, the ridges 56 may be separated by conductor receiving recesses58 operating in a manner similar to the recesses 42 described hereinabove. Accordingly, each of the recesses 58 may be selectivelydimensioned to at least partially or fully accept the external conductor22 therewithin to insure electrical engagement between the inner sleeve,the sheath 24, and the external conductor 22.

I claim:

1. Means for joining an external conductor to the sheath of ametallically sheathed cable comprising: a first hollow metallic sleevemember having an inner surface and an outer surface; a second hollowmetallic sleeve member having an inner surface and an outer surface,said first sleeve member being arranged to fit coaxially within saidsecond sleeve member while providing a predetermined annular gaptherebetween for receiving a portion of the sheath of a metallicallysheathed cable within said gap; and insulation piercing sheath engagingmeans selectively positioned about at least one of said first memberouter surface and said second member inner surface; said second sleevemember being compressible about said first sleeve member so as to causesaid sheath engaging means to engage such cable sheath portion and anexternal conductor interposed within said gap to electrically join suchexternal conductor to such cable sheath portion at least through one ofsaid first sleeve member and said second sleeve member upon thecompression of said second sleeve member about said first sleeve member,said first sleeve member outer surface having at least one generallylongitudinally extending recess arranged to at least partiallyaccommodate a given length of such external conductor therewithin.

2. Means for joining an external conductor to the sheath of ametallically sheathed cable comprising: a first hollow metallic sleevemember having an inner surface and an outer surface; a second hollowmetallic sleeve member having an inner surface and an outer surface,said first sleeve member being arranged to fit coaxially within saidsecond sleeve member while providing a predetermined annular gaptherebetween for receiving a portion of the sheath of a metallicallysheathed cable within said gap; and insulation piercing sheath engagingmeans selectively positioned about at least one of said first memberouter surface and said second member inner surface; said second sleevemember being compressible about said first sleeve member so as to causesaid sheath engaging means to engage such cable sheath portion and anexternal conductor interposed within said gap to electrically join suchexternal conductor to such cable sheath portion at least through one ofsaid first sleeve member and said second sleeve member upon thecompression of said second sleeve member about said first sleeve member,said means further comprising longitudinally extending slotted portionsdisposed selectively about said outer surface of said second sleevemember to at least partially relieve the stress in said second sleevemember as said second sleeve member is compressed about said firstsleeve member, said sheath engaging means comprising longitudinallyextending recessed portions disposed selectively within said innersurface of said second sleeve member and in general coincidence withsaid longitudinally extending slotted portions disposed about saidsecond sleeve member outer surface.

3. Means for joining an external conductor to the sheath of ametallically sheathed cable comprising: a first hollow metallic sleevemember having an inner surface and an outer surface; a second hollowmetallic sleeve member having an inner surface and an outer surface,said first sleeve member being arranged to fit coaxially within saidsecond sleeve member while providing a predetermined annular gaptherebetween for receiving a portion of the sheath of a metallicallysheathed cable within said gap; and insulation piercing sheath engagingmeans selectively positioned about at least one of said first memberouter surface and said second member inner surface; said second sleevemember being compressible about said first sleeve member so as to causesaid sheath engaging means to engage such cable sheath portion and anexternal conductor 3 ,897, 1 27 7 8 interposed within said gap toelectrically join such exsheath engaging means comprising a series ofraised ternal conductor such cable sheath Porno least ridges disposed ina generally helical pattern about said through one of said first sleevemember and said second sleeve member upon the compression of said secondsleeve member about said first sleeve member, said first sleeve memberouter surface.

1. Means for joining an external conductor to the sheath of ametallically sheathed cable comprising: a first hollow metallic sleevemember having an inner surface and an outer surface; a second hollowmetallic sleeve member having an inner surface and an outer surface,said first sleeve member being arranged to fit coaxially within saidsecond sleeve member while providing a predetermined annular gaptherebetween for receiving a portion of the sheath of a metallicallysheathed cable within said gap; and insulation piercing sheath engagingmeans selectively positioned about at least one of said first memberouter surface and said second member inner surface; said second sleevemember being compressible about said first sleeve member so as to causesaid sheath engaging means to engage such cable sheath portion and anexternal conductor interposed within said gap to electrically join suchexternal conductor to such cable sheath portion at least through one ofsaid first sleeve member and said second sleeve member upon thecompression of said second sleeve member about said first sleeve member,said first sleeve member outer surface having at least one generallylongitudinally extending recess arranged to at least partiallyaccommodate a given length of such external conductor therewithin. 2.Means for joining an external conductor to the sheath of a metallicallysheathed cable comprising: a first hollow metallic sleeve member havingan inner surface and an outer surface; a second hollow metallic sleevemember having an inner surface and an outer surface, said first sleevemember being arranged to fit coaxiAlly within said second sleeve memberwhile providing a predetermined annular gap therebetween for receiving aportion of the sheath of a metallically sheathed cable within said gap;and insulation piercing sheath engaging means selectively positionedabout at least one of said first member outer surface and said secondmember inner surface; said second sleeve member being compressible aboutsaid first sleeve member so as to cause said sheath engaging means toengage such cable sheath portion and an external conductor interposedwithin said gap to electrically join such external conductor to suchcable sheath portion at least through one of said first sleeve memberand said second sleeve member upon the compression of said second sleevemember about said first sleeve member, said means further comprisinglongitudinally extending slotted portions disposed selectively aboutsaid outer surface of said second sleeve member to at least partiallyrelieve the stress in said second sleeve member as said second sleevemember is compressed about said first sleeve member, said sheathengaging means comprising longitudinally extending recessed portionsdisposed selectively within said inner surface of said second sleevemember and in general coincidence with said longitudinally extendingslotted portions disposed about said second sleeve member outer surface.3. Means for joining an external conductor to the sheath of ametallically sheathed cable comprising: a first hollow metallic sleevemember having an inner surface and an outer surface; a second hollowmetallic sleeve member having an inner surface and an outer surface,said first sleeve member being arranged to fit coaxially within saidsecond sleeve member while providing a predetermined annular gaptherebetween for receiving a portion of the sheath of a metallicallysheathed cable within said gap; and insulation piercing sheath engagingmeans selectively positioned about at least one of said first memberouter surface and said second member inner surface; said second sleevemember being compressible about said first sleeve member so as to causesaid sheath engaging means to engage such cable sheath portion and anexternal conductor interposed within said gap to electrically join suchexternal conductor to such cable sheath portion at least through one ofsaid first sleeve member and said second sleeve member upon thecompression of said second sleeve member about said first sleeve member,said sheath engaging means comprising a series of raised ridges disposedin a generally helical pattern about said first sleeve member outersurface.